Sheets of apertured films, woven fabrics and nonwoven materials are widely used in many types of products such as, for example, personal care products, garments, medical fabrics and the like. Some sheets made from certain inexpensive raw materials could have an even wider range of applications in these products if the sheets could be designed to have enhanced properties or attributes.
For example, polyolefins are widely used in the manufacture of sheets of apertured films, woven fabrics, and nonwoven materials. Many types of polyolefin sheets tend to be hydrophobic and relatively chemically inert. That is, the low surface free energy of polyolefins (e.g., polypropylene) and their relatively chemically inert nature render many unmodified polyolefins ill-suited for providing attributes other than those based on hydrophobic interactions.
In the past, chemical coatings and/or internal additives have been added to sheets of materials to impart desired properties. Many of these coatings and/or additives present problems related to cost, effectiveness, durability and/or the environment.
It has been proposed that biofunctional materials (e.g., proteins) can be deposited from solutions onto different substrates (i.e., sheets of materials) to modify the surface properties of the substrates and/or serve as a functionalized surface that can be chemically reactive. However, many of the economically desirable substrates (e.g., substrates formed of polymers such as polyolefins) have surfaces that are unsuitable for the rapid and inexpensive deposition of biofunctional materials, especially when durable, tightly-bound coatings of satisfactory adherence are desired. If the coatings are not durable, then modifications to the coatings would generally lack durability.
Even if inexpensive, durable, tenacious coatings could be adhered to an economically desirable substrate, coatings composed solely of biofunctional materials may have limitations, especially if the coatings lacked the desired chemical characteristics.
Thus, there is still a need for a simple method of producing a durable and chemically charged modified coating on an unmodified, relatively inert, hydrophobic substrate. A need exists for a practical method of producing a durable and chemically charged modified coating on an unmodified, relatively inert, polyolefin substrate. A need also exists for a chemically charge modified permeable sheet (i.e., a relatively inert, hydrophobic permeable sheet having a durable, chemically charge modified coating). A need also exists for a fibrous and/or apertured film-like material having a durable, chemically charge modified coating. A need also exists for fibrous and/or apertured film-like substrates formed from a relatively inert, hydrophobic material (e.g., a polyolefin) and having a durable, chemically charge modified coating of readily available, inexpensive materials, especially if such a coated material can be produced in a high-speed manufacturing process. Meeting these needs are important since it is both economically and environmentally desirable to substitute relatively complex chemical surface modification and/or functionalization of inexpensive (and often recyclable) substrates with inexpensive, readily available materials.